Yanmar 3TNV82A Troubleshooting Manual page 188

FAILURE DIAGNOSIS
3. Check of harness continuity:
• Remove the EGR valve from the harness, and remove E-ECU from the harness.
• Check the harness continuity using a circuit tester.
Terminal
Motor coil (downstream side)
E31(E21/E11/E01)
[Between E-ECU and EGR connector]
Motor coil (upstream side) E48
[Between E-ECU and EGR connector]
Between E31 (E21/E11/E01) and
GND/E28/E45/E47
Between E31 (E21/E11/E01) and
E43/E48
NG
OK
4. Movement check of the EGR:
• Connect the 2G eco-checker harness between E-ECU and machine's harness (for details, see [How to
use the 2G eco-checker harness] (P.1-135). And connect the all connectors (EGR valve, E-ECU).
• Connect the diagnosis tool, and log in to the diagnosis tool after key switch turning-on.
• Activate each step motor of the EGR valve by the diagnosis tool "Diagnosis Test: Active control", and
measure the voltage between step motor coil terminals E31-E45, (E21-E45, E11-E45, E01-E45)
respectively.
ON/OFF setting status
ON
OFF
NG
OK
1-186
• Check if the harness is damaged, or if the wiring is correct.
• Replace the harness.
Check the movement of the EGR by the diagnosis tool. → Go to [4. Movement
check of the EGR:]
Voltage
1.75[V] and below OK: normal
Over 1.75[V]
2.5[V] and above
Under 2.5[V]
• Check if the harness is damaged, or if the wiring is correct.
• Replace the harness.
Replace the E-ECU.
Method and Procedure of Failure Diagnosis
Continuity
Available OK: normal
Unavailable NG: harness disconnection
Available OK: normal
Unavailable NG: harness disconnection
Unavailable OK: normal
Available NG: harness short-circuited with GND
Unavailable OK: normal
NG: Harness short-circuited with power
Available
supply
NG: Harness short-circuited with power supply or E-
ECU fault
OK: normal
NG: Harness short-circuited with GND or E-ECU fault
TNV DI Service Manual
Status
Status